So many souls await
Dark Harvest
Damaging a Champion below 50% health deals
adaptive damage and harvests their soul, permanently increasing Dark Harvest's damage by 11.
Dark Harvest damage: 30 (+11 damage per soul) (+0.1 bonus AD) (+0.05 AP)
Cooldown: 35s (resets to 1.0s on takedown)Why?
Dark Harvest's execution damage play pattern synergizes well with Karthus' [R] when you're looking to pick up late-hit kills.
Taste of Blood
Heal when you damage an enemy champion.
Healing: 16-40 (+0.1 bonus AD, +0.05 AP) health (based on level)
Cooldown: 20sWhy?
Taste of Blood makes your lane phase sustain a lot more reliable.
Grisly Mementos
Collect 1 memento on champion
takedowns , up to 18 total.
Gain 6 Trinket Haste for each collected. In game modes where vision Trinkets do not exist, instead gain 3 Summoner Spell Haste.Why?
Grisly Mementos's kill/assist stacking is easy to build up with a few early well-timed [R]s.
Ultimate Hunter
Your ultimate gains
6 Ability Haste, plus an additional5 Ability Haste per Bounty Hunter stack. Bounty Hunter stacks are earned the first time you get a takedown on each enemy champion.Why?
Ultimate Hunter is the perfect rune choice here for Karthus as the stacks are easy to pick up across the map with [R] as well as keeping your main ability on as short of a cooldown as possible.
Presence of Mind
Damaging an enemy champion restores 6-50 (80% for ranged) mana or 6 energy.
Takedowns restore 15% of your maximum mana or energy.
Cooldown for damage restoration: 8sWhy?
Like Ultimate Hunter, this build is entirely focus around your [R] execute damage and keeping on as low of a cooldown as possible.
Coup de Grace
Deal 8% more damage to champions who have less than 40% health.
Why?
Coup De Grace further empowers your ability to lat hit champions with [R], especially when combined with Dark Harvest.
Rest in Peace
Summon Aery
Damaging enemy champions with basic attacks or abilities sends Aery to them, dealing 10 - 50 based on level (+
0.05 AP ) (+0.1 bonus AD ).
Empowering or protecting allies with abilities sends Aery to them, shielding them for 30 - 100 based on level (+0.05 AP ) (+0.1 bonus AD ).
Aery cannot be sent out again until she returns to you.Why?
Aery provides Karthus with reliable and repeatable damage output. When spamming [Q] in lane the extra bit of chip damage adds up to be an important factor in bringing the enemy to kill range.
Manaflow Band
Hitting an enemy champion with an ability permanently increases your maximum mana by 25, up to 250 mana.
After reaching 250 bonus mana, restore 1% of your missing mana every 5 seconds.
Cooldown: 15 secondsWhy?
Manaflow Band empowers your early game mana sustain so that you're able to continue harassing with [Q] and have enough mana for those critical [R] casts in the mid game.
Transcendence
Gain bonuses upon reaching the following levels:
Level 5: +5Ability Haste
Level 8: +5Ability Haste
Level 11: On Champion takedown, reduce the remaining cooldown of basic abilities by 20%.Why?
The extra bit of CDR from Transcendence allows you to opt into Magic Pen and raw AP in the mid game for more damage outout.
Gathering Storm
Every 10 min gain AP or AD,
adaptive .
10 min: + 8 AP or 5 AD
20 min: + 24 AP or 14 AD
30 min: + 48 AP or 29 AD
40 min: + 80 AP or 48 AD
50 min: + 120 AP or 72 AD
60 min: + 168 AP or 101 AD
etc...Why?
Gathering Storm on Karthus makes you an absolute late game monster able to completely take over a game with your [R].
Coup de Grace
Deal 8% more damage to champions who have less than 40% health.
Why?
Karth can make great use of Coup De Grace, synergizing well with both is **[R] for executions**, and when he's **in his passive** form looking to finish a target.
Presence of Mind
Damaging an enemy champion restores 6-50 (80% for ranged) mana or 6 energy.
Takedowns restore 15% of your maximum mana or energy.
Cooldown for damage restoration: 8sWhy?
Presence of Mind's mana and [R] refund is massive for Karthus. When paired with CDR and Ultimate Hat, a few kills/assists will greatly reduce your [R] cooldown for another fight.